Test handlers are frequently used for testing IC devices in combination with IC testers for automatically transferring IC devices to and from test heads of the IC testers. Test handlers are classified into two types, a vertical transfer type in which IC devices are transferred from the higher positions to the lower positions by their own gravity, and a horizontal transfer type in which IC devices are transferred along the horizontal surface of the test handler. This invention is directed to the horizontal transfer type test handler.
In a horizontal transfer test handler, a plurality of IC devices to be tested are provided on a device tray and horizontally transferred to a test head of an IC tester. Various test signals are supplied to the IC devices at the test head, and the resultant output signals from the IC devices are evaluated by the IC tester. The tested IC devices are classified based on the test results and transferred to the corresponding device trays.
An example of horizontal transfer test handler in the conventional technology is shown in FIGS. 6-8. A horizontal transfer test handler is a robot mechanism that transfers IC devices in horizontal directions, places the IC devices on the test head of the IC tester, receives the IC devices that have been tested, and sorts the IC devices on the device trays on the basis of the test results.
As shown in FIG. 6, the horizontal transfer test handler 30 in the prior art is comprised of a device transfer mechanism 13 to pick, transfer, and place the IC devices, a mobile arm 12 to allow movements of the device transfer mechanism 13 in a Y direction, an X direction rail to allow movements of the mobile arm 12 in an X direction, a loader area 22 for loading a device tray 43 having a plurality of IC devices to be tested, an unloader area 23 for receiving the IC devices that have passed the test on a device tray 43, sorter areas 24 and 25 for sorting the tested IC devices that have failed in the test on respective device trays 43, a heater area 27 for applying heat to the IC devices to be tested so that the IC devices are tested under a high temperature environment, an empty tray area 26 for placing a device tray 43 emptied in the loader area 22, and change kits 41 and 42 for accommodating different sizes and types of device trays and IC sockets.
As shown in FIG. 7, the device transfer mechanism 13 is comprised of a suction pad 16 that performs suction (pick operation) and suction release (place operation) processes for IC devices 10 stored on a device tray 43. The suction force is created, for example, by a vacuum pressure. A suction arm 15 allows movements of the suction pad 16 in a Z (up-down) direction.
In FIG. 6, the horizontal transfer test handler 30 is connected to a test head 50 that is electrically connected to an IC tester 51. The test head 50 has an IC socket 40 that acts as an interface between the IC device 10 under test and the test head 50. The IC socket 40 mounted on the test head 50 transmits electric signals from each of its contact terminals to a corresponding device pin during the test of the IC device 10.
The change kits are groups of mechanical parts for adjusting the test handler 30 to various types and sizes of IC devices and the device trays by replacing all or portions of the mechanical parts. The kind of the change kit includes a change kit 42 that supports the device tray 43 of different sizes and types. The device tray 43 is mounted on the loader area 22 while being adjusted its position by the change kit 42. The change kit 41 performs an accurate mechanical positioning for the IC socket on the test head 50. Thus, the change kit 41 adjusts the position of the IC socket 40 relative to the test head 50 in response to the size and types of the IC devices to be tested.
FIG. 8 is a schematic diagram showing a control section of the horizontal transfer test handler. The control section is comprised of an input/output means 61 for receiving a control program and input data and generating test information or other test results, a controller 62 that interprets and executes the control program and input data, a device transfer mechanism driver 63 controlled by the controller 62. Based on the drive signals from the driver 63, the device transfer mechanism 13 is moved in the X, Y, and Z directions. Namely, a pulse motor (not shown) is controlled to drive the suction arm 15 in the Z direction. The mobile arm 12 is driven in the X direction while the device transfer mechanism 13 is driven in the Y direction, respectively, by the drive signals from the driver 63.
Referring back to FIG. 6, the horizontal transfer test handler 30 transfers the IC device 10 in a horizontal direction, and presses the lead pins of the IC device 10 to the contact terminals of the IC socket 40 mounted on the test head 50. Test signals are applied to the IC device from the IC tester through the IC socket 40. The resultant signals from the IC device 10 are transmitted to the IC tester through the IC socket 40 and evaluated by comparing the resultant signals with expected data. The IC tester determines pass or fail of the IC devices 10. The horizontal transfer test handler 30 sorts the tested IC devices 10 according to the test results.
The IC devices 10 to be tested by such a system of the test handler and IC tester are IC, LSI circuits and VLSI circuits. Even when the functions are identical, IC devices are put in different type and size of packages to meet the needs in the market. For example, the kinds of packages include SOP (Small Outline Package), QFP (Quad Flat Package), BGA (Ball Grid Array Package), and so on. The number of pins of the IC devices to be connected to outside electrodes also extends to a wide range, such as from a few pins to several hundred pins. The distance between the two adjacent pins of the IC devices, i.e., a pin pitch, is very small, such as from 0.25 mm to 0.8 mm.
The device tray 43 stores IC devices 10 in its hole-like seats where each of the IC devices is positioned by tapered walls of the seat. For example, the device tray 43 shown in FIG. 6 can store 24 (4.times.6=24) devices. The size of the device tray varies, for instance, from 100 mm to 140 mm in width, and from 206 mm to 330 mm in length.
The operation and function of the horizontal transfer test handler 30 is explained in the following.
Prior to the start of the test, the IC devices 10 to be tested are stored in the device tray 43 which is loaded on the loader area 22 of the test handler 30. Test programs and necessary data for testing the IC devices 10 are installed in the test handler 30 through the input/output means 61. The necessary data for the test includes the information on the kinds of IC devices 10 to be tested, the package types of the IC devices 10, the number of device pins, and the size of the device tray 43.
The suction arm 15 moves in the Z direction and the suction pad 16 performs the suction process on the IC devices 10 stored in the device tray 43. While sucking the IC device 10 at the tip of the suction pad 16, the mobile arm 12 and the device transfer mechanism 13 move in the X and Y directions to the heater area 27 to place the IC device 10 thereon so that the IC device is provided with heat. Then the IC device 10 heated in the heater area 27 is again picked up by the suction pad 16 and moved to the IC socket 40 on the test head 50 to connect the lead pins of the IC device 10 to the contact terminals of the IC socket 40.
When the IC device is connected to the IC socket 40, the test of the IC device 10 is carried out by the IC tester. After the test, the device transfer mechanism 13 transfers the IC devices that have been tested to several areas based on the test results. Good IC devices are transferred to a device tray 43 on the unloader area 23 while the defective IC devices are transferred to device trays 43 on the sort areas 24 and 25 to be classified based on types of defect.
When the device tray 43 in the loader area 22 is emptied because all of the IC devices 10 are removed therefrom for the test, the device tray 43 is transferred to the empty tray area 26. The above noted process is repeated for the IC devices on the next device tray 43 mounted on the loader area 23 of the test handler 30.
As explained above, there are a variety of packages of the IC devices 10 to be handled by the test handler 30. Accordingly, the device trays 43 come with various types corresponding to the types of the packages. An operator of the test handler 30 has to provide the data through the input/output means 61 indicating the types of the packages and trays. As a consequence, errors may be involved in such a data input process because the types of packages and trays are rather complicated.
Moreover, since the pin pitch of the IC devices is very small, accurate mechanical positioning is necessary for establishing the electrical connection between the lead pins of IC device to be tested and the contact terminals of the IC socket 40. To improve the mechanical positioning, a gap between the taper wall of the device tray 43 and the IC device 10 may be decreased. However, such a solution may cause a further problem such as jamming because of the decreased play in the device tray. Further, the change kits 41 and 42 will be required to have a higher level of mechanical finishing to more accurately positioning the IC socket 40 and the device trays 43.